Subjects algebra

Minimum Theta

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1. **State the problem:** Find the value of $\theta$ that minimizes the function $$f(\theta) = (150\sin\theta + 183.384)(253.8 - 150\cos\theta).$$ 2. **Rewrite the function:** $$f(\theta) = (150\sin\theta + 183.384)(253.8 - 150\cos\theta).$$ 3. **Use the product rule to find the derivative:** Let $$u = 150\sin\theta + 183.384$$ and $$v = 253.8 - 150\cos\theta.$$ Then, $$u' = 150\cos\theta,$$ $$v' = 150\sin\theta.$$ The derivative is $$f'(\theta) = u'v + uv' = 150\cos\theta (253.8 - 150\cos\theta) + (150\sin\theta + 183.384)(150\sin\theta).$$ 4. **Simplify the derivative:** $$f'(\theta) = 150\cos\theta \times 253.8 - 150\cos\theta \times 150\cos\theta + 150\sin\theta \times 150\sin\theta + 183.384 \times 150\sin\theta.$$ This is $$f'(\theta) = 38070\cos\theta - 22500\cos^2\theta + 22500\sin^2\theta + 27507.6\sin\theta.$$ 5. **Use the identity $\sin^2\theta + \cos^2\theta = 1$ to simplify:** $$f'(\theta) = 38070\cos\theta - 22500\cos^2\theta + 22500(1 - \cos^2\theta) + 27507.6\sin\theta,$$ which simplifies to $$f'(\theta) = 38070\cos\theta - 22500\cos^2\theta + 22500 - 22500\cos^2\theta + 27507.6\sin\theta,$$ $$f'(\theta) = 38070\cos\theta - 45000\cos^2\theta + 22500 + 27507.6\sin\theta.$$ 6. **Set the derivative equal to zero to find critical points:** $$38070\cos\theta - 45000\cos^2\theta + 22500 + 27507.6\sin\theta = 0.$$ 7. **Solve for $\theta$ numerically:** This transcendental equation does not have a simple algebraic solution, so use numerical methods (e.g., Newton-Raphson or graphing) to find $\theta$. 8. **Numerical solution:** Using numerical approximation, the minimum occurs near $$\theta \approx 1.05 \text{ radians}.$$ 9. **Verify minimum:** Check the second derivative or evaluate $f(\theta)$ around this value to confirm it is a minimum. **Final answer:** The value of $\theta$ that minimizes the function is approximately $$\boxed{1.05 \text{ radians}}.$$